using System;

public class Program

{

    public static string[] vietel = new string[] {"086","096","097","098","032","033","034","035","036","037","038","039"};

    public static string[] vina = new string[] {"088","091","094","083","084","085","081","082"};

    public static string[] mobi = new string[] {"089","090","093","070","079","077","076","078"};

    public static string[] sdt = new string[10];

    public static void Main()

    {

        int phone;

        Console.WriteLine("nhap so luong sdt");

        int i = Convert.ToInt32(Console.ReadLine());

        for ( phone = 0; phone < i; phone++)

             {

            Console.WriteLine("nhap so dien thoai " + (phone + 1));

            sdt[phone] = Console.ReadLine();

             }

        for ( phone = 0; phone < i; phone ++)

        {

        int k = processoper(sdt[phone]);

        switch (k)

        {

            case 1:

                Console.WriteLine(sdt[phone] + " so viettel");

                break;

            case 2:

                Console.WriteLine(sdt[phone] + " so vina");

                break;

            case 3:

                Console.WriteLine(sdt[phone] + " so mobi");

                break;

            case 4:

                Console.WriteLine(sdt[phone] + " khong thuoc nha mang nao");

                break;

        }

        }

        Console.ReadLine();

    }

    public static int processoper(string number)

    {

        int k;

        number = processnumber(number);

​

        bool viettel = processviettel(number);

        bool vina = processvina(number) ;

        bool mobi = processmobi(number) ;

        if ( viettel == true)

        {

            k =1;

        }

        else if ( vina == true)

        {

            k =2;

        }

        else if ( mobi == true)

        {

            k =3;

        }

        else 

        {

            k =4;

        }

        return k;

    }

    public static string processnumber (string phone)

    {

        string number = phone.Substring(0,3);

            return number;

    }

    public static bool processviettel (string number)

    {

        int i;

        for (i = 0; i < vietel.Length; i++)

        {

            if ( number == vietel[i])

            {

                return true;

            }

        }

        return false;

    }

    public static bool processvina (string number)

    {

        int i;

        for (i = 0; i < vina.Length; i++)

        {

            if ( number == vina[i])

            {

                return true;

            }

        }

        return false;

    }

    public static bool processmobi (string number)

    {

        int i;

        for (i = 0; i < mobi.Length; i++)

        {

            if ( number == mobi[i])

            {

                return true;

            }

        }

        return false;

            }

}